Proteus IgG antibodies and C-reactive protein in English, Norwegian and Spanish patients with rheumatoid arthritis

The distribution of Proteus antibody Levels was compared in English, Norweg ian and Spanish patients with rheumatoid arthritis (RA). Using an indirect immunofluorescence method, the IgG antibody titre against Proteus mirabilis was measured in the sera of 27 English, 53 Norwegian and 34 Spanish patien ts with RA and divided into active and inactive disease groups according to the serum C-reactive protein (CRP) level (greater than or equal to 10 mg/l ). Serum samples were also collected from 25 English, 30 Norwegian and 14 S panish healthy individuals who served as controls. The levels of Proteus Ig G antibodies were significantly higher in the sera of active RA patients (p <0.001) when compared with the corresponding healthy controls, whether the se groups belonged to the English, Norwegian or Spanish populations. Furthe rmore, active RA patients from each country showed significantly higher lev els of Proteus antibodies when compared with inactive English (p<0.01), Nor wegian (p<0.001) or Spanish (p<0.001) RA patients. Finally, a significant c orrelation was observed between Proteus Ige antibody Levels and the CRP con centrations in RA patients whether each population was tested individually or all together (p<0.001). The increased levels of Proteus antibodies in RA patients from three different European countries support the concept of a possible aetiopathogenetic role for Proteus microorganisms in the developme nt of RA.